
/* Copyright 1998 by the Massachusetts Institute of Technology.
 * Copyright (C) 2009 by Jakub Hrozek <jhrozek@redhat.com>
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

#include "ares_setup.h"

#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_ARPA_NAMESER_H
#include <arpa/nameser.h>
#else
#include "nameser.h"
#endif
#ifdef HAVE_ARPA_NAMESER_COMPAT_H
#include <arpa/nameser_compat.h>
#endif

#include "ares.h"
#include "ares_dns.h"
#include "ares_data.h"
#include "ares_private.h"

/* AIX portability check */
#ifndef T_NAPTR
#define T_NAPTR 35 /* naming authority pointer */
#endif

int ares_parse_naptr_reply(const unsigned char* abuf, int alen,
    struct ares_naptr_reply** naptr_out)
{
    unsigned int qdcount, ancount, i;
    const unsigned char *aptr, *vptr;
    int status, rr_type, rr_class, rr_len;
    long len;
    char *hostname = NULL, *rr_name = NULL;
    struct ares_naptr_reply* naptr_head = NULL;
    struct ares_naptr_reply* naptr_last = NULL;
    struct ares_naptr_reply* naptr_curr;

    /* Set *naptr_out to NULL for all failure cases. */
    *naptr_out = NULL;

    /* Give up if abuf doesn't have room for a header. */
    if (alen < HFIXEDSZ)
        return ARES_EBADRESP;

    /* Fetch the question and answer count from the header. */
    qdcount = DNS_HEADER_QDCOUNT(abuf);
    ancount = DNS_HEADER_ANCOUNT(abuf);
    if (qdcount != 1)
        return ARES_EBADRESP;
    if (ancount == 0)
        return ARES_ENODATA;

    /* Expand the name from the question, and skip past the question. */
    aptr = abuf + HFIXEDSZ;
    status = ares_expand_name(aptr, abuf, alen, &hostname, &len);
    if (status != ARES_SUCCESS)
        return status;

    if (aptr + len + QFIXEDSZ > abuf + alen) {
        ares_free(hostname);
        return ARES_EBADRESP;
    }
    aptr += len + QFIXEDSZ;

    /* Examine each answer resource record (RR) in turn. */
    for (i = 0; i < ancount; i++) {
        /* Decode the RR up to the data field. */
        status = ares_expand_name(aptr, abuf, alen, &rr_name, &len);
        if (status != ARES_SUCCESS) {
            break;
        }
        aptr += len;
        if (aptr + RRFIXEDSZ > abuf + alen) {
            status = ARES_EBADRESP;
            break;
        }
        rr_type = DNS_RR_TYPE(aptr);
        rr_class = DNS_RR_CLASS(aptr);
        rr_len = DNS_RR_LEN(aptr);
        aptr += RRFIXEDSZ;
        if (aptr + rr_len > abuf + alen) {
            status = ARES_EBADRESP;
            break;
        }

        /* Check if we are really looking at a NAPTR record */
        if (rr_class == C_IN && rr_type == T_NAPTR) {
            /* parse the NAPTR record itself */

            /* Allocate storage for this NAPTR answer appending it to the list */
            naptr_curr = ares_malloc_data(ARES_DATATYPE_NAPTR_REPLY);
            if (!naptr_curr) {
                status = ARES_ENOMEM;
                break;
            }
            if (naptr_last) {
                naptr_last->next = naptr_curr;
            } else {
                naptr_head = naptr_curr;
            }
            naptr_last = naptr_curr;

            vptr = aptr;
            naptr_curr->order = DNS__16BIT(vptr);
            vptr += sizeof(unsigned short);
            naptr_curr->preference = DNS__16BIT(vptr);
            vptr += sizeof(unsigned short);

            status = ares_expand_string(vptr, abuf, alen, &naptr_curr->flags, &len);
            if (status != ARES_SUCCESS)
                break;
            vptr += len;

            status = ares_expand_string(vptr, abuf, alen, &naptr_curr->service, &len);
            if (status != ARES_SUCCESS)
                break;
            vptr += len;

            status = ares_expand_string(vptr, abuf, alen, &naptr_curr->regexp, &len);
            if (status != ARES_SUCCESS)
                break;
            vptr += len;

            status = ares_expand_name(vptr, abuf, alen, &naptr_curr->replacement, &len);
            if (status != ARES_SUCCESS)
                break;
        }

        /* Don't lose memory in the next iteration */
        ares_free(rr_name);
        rr_name = NULL;

        /* Move on to the next record */
        aptr += rr_len;
    }

    if (hostname)
        ares_free(hostname);
    if (rr_name)
        ares_free(rr_name);

    /* clean up on error */
    if (status != ARES_SUCCESS) {
        if (naptr_head)
            ares_free_data(naptr_head);
        return status;
    }

    /* everything looks fine, return the data */
    *naptr_out = naptr_head;

    return ARES_SUCCESS;
}
